The present invention relates to an automobile steering device. In particular, the present invention relates to the structure of a steering device used in automobiles having parts such as: an engine mounted at a front section of a chassis frame formed by connecting a plurality of cross members to a left and a right side member; a steering mechanism for steering the front wheels; and a steering gear box, containing a steering gear, which is attached to a cross member and connected to the steering mechanism. More specifically, the present invention relates to a connecting structure between a steering shaft and a middle shaft in a steering column.
In automotive steering devices, the steering column includes a two-piece middle shaft as disclosed in Japanese Laid-Open Patent Publication Number 6-107187. In a typical embodiment, the steering column is disposed in an engine compartment. The lower middle shaft, one of the two pieces composing the middle shaft, is connected to a steering gear which is, in turn, connected to a steering device that steers the front wheels. A section of the middle shaft extends into a driver's cabin, which is partitioned from the engine compartment by a dash panel. The upper middle shaft is connected to the steering shaft in the driver's cabin. The upper and lower middle shafts are then connected in the driver's cabin by a joint.
The joint connecting the upper and lower middle shaft sections is tightened at the front end of the driver's cabin. A bolt is inserted into the bolt hole in this joint in a direction along the width axis of the vehicle. The bolt is then tightened to connect the two-part middle shaft.
In addition to an engine, the engine compartment of an automobile generally contains engine accessories such as radiators. A design preferably allows these accessories to be arranged in the small space above the chassis frame to minimize open space, thus providing a compact engine compartment space. A steering column is also disposed inside this engine compartment, for transferring an operating force from the driver to the steering mechanism used to steer the front wheels.
Thus, demand exists for a steering column appropriate for such a small, compact space. The connecting section of the steering column should be accessible from the engine compartment so that installation on production lines and automotive maintenance is made more efficient.
Another issue relating to ease of installation of the steering column relates to the bolt at the joint between the middle shaft and the steeling shaft. In production lines and repair shops, the bolt that tightens this joint must be manipulated from a standing position. Thus, the direction in which the bolt is inserted or tightened should be suitable for someone operating from above the engine compartment.
For similar reasons, it is desirable for the middle shaft to be installed without having to be rotated. This allows the bolt to be inserted roughly parallel to a flat section disposed on the middle shaft at a prescribed distance from the end of the middle shaft. The flat section extends in the direction of the shaft and allows the overall length of the steering column to be adjusted.